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Wed, 08 Feb 2023 10:00:08 +0000 Date: Wed, 08 Feb 2023 10:00:06 +0000 Message-ID: <86o7q4zdcp.wl-maz@kernel.org> From: Marc Zyngier To: David Matlack Cc: Paolo Bonzini , James Morse , Suzuki K Poulose , Oliver Upton , Zenghui Yu , Huacai Chen , Aleksandar Markovic , Anup Patel , Atish Patra , Paul Walmsley , Palmer Dabbelt , Albert Ou , Sean Christopherson , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, Raghavendra Rao Ananta Subject: Re: [PATCH v2 2/7] KVM: arm64: Use kvm_arch_flush_remote_tlbs() In-Reply-To: <20230126184025.2294823-3-dmatlack@google.com> References: <20230126184025.2294823-1-dmatlack@google.com> <20230126184025.2294823-3-dmatlack@google.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/28.2 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: dmatlack@google.com, pbonzini@redhat.com, james.morse@arm.com, suzuki.poulose@arm.com, oliver.upton@linux.dev, yuzenghui@huawei.com, chenhuacai@kernel.org, aleksandar.qemu.devel@gmail.com, anup@brainfault.org, atishp@atishpatra.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, seanjc@google.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, rananta@google.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230208_020015_122724_9D75AC3E X-CRM114-Status: GOOD ( 28.79 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, 26 Jan 2023 18:40:20 +0000, David Matlack wrote: > > Use kvm_arch_flush_remote_tlbs() instead of > CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL. The two mechanisms solve the same > problem, allowing architecture-specific code to provide a non-IPI > implementation of remote TLB flushing. > > Dropping CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL allows KVM to standardize > all architectures on kvm_arch_flush_remote_tlbs() instead of maintaining > two mechanisms. > > Opt to standardize on kvm_arch_flush_remote_tlbs() since it avoids > duplicating the generic TLB stats across architectures that implement > their own remote TLB flush. > > This adds an extra function call to the ARM64 kvm_flush_remote_tlbs() > path, but that is a small cost in comparison to flushing remote TLBs. > > No functional change intended. > > Signed-off-by: David Matlack > --- > arch/arm64/include/asm/kvm_host.h | 3 +++ > arch/arm64/kvm/Kconfig | 1 - > arch/arm64/kvm/mmu.c | 6 +++--- > virt/kvm/Kconfig | 3 --- > virt/kvm/kvm_main.c | 2 -- > 5 files changed, 6 insertions(+), 9 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index 113e20fdbb56..062800f1dc54 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -998,6 +998,9 @@ int __init kvm_set_ipa_limit(void); > #define __KVM_HAVE_ARCH_VM_ALLOC > struct kvm *kvm_arch_alloc_vm(void); > > +#define __KVM_HAVE_ARCH_FLUSH_REMOTE_TLBS > +int kvm_arch_flush_remote_tlbs(struct kvm *kvm); > + > static inline bool kvm_vm_is_protected(struct kvm *kvm) > { > return false; > diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig > index ca6eadeb7d1a..e9ac57098a0b 100644 > --- a/arch/arm64/kvm/Kconfig > +++ b/arch/arm64/kvm/Kconfig > @@ -25,7 +25,6 @@ menuconfig KVM > select MMU_NOTIFIER > select PREEMPT_NOTIFIERS > select HAVE_KVM_CPU_RELAX_INTERCEPT > - select HAVE_KVM_ARCH_TLB_FLUSH_ALL > select KVM_MMIO > select KVM_GENERIC_DIRTYLOG_READ_PROTECT > select KVM_XFER_TO_GUEST_WORK > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index 01352f5838a0..8840f65e0e40 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -80,15 +80,15 @@ static bool memslot_is_logging(struct kvm_memory_slot *memslot) > } > > /** > - * kvm_flush_remote_tlbs() - flush all VM TLB entries for v7/8 > + * kvm_arch_flush_remote_tlbs() - flush all VM TLB entries for v7/8 > * @kvm: pointer to kvm structure. > * > * Interface to HYP function to flush all VM TLB entries > */ > -void kvm_flush_remote_tlbs(struct kvm *kvm) > +int kvm_arch_flush_remote_tlbs(struct kvm *kvm) > { > - ++kvm->stat.generic.remote_tlb_flush_requests; > kvm_call_hyp(__kvm_tlb_flush_vmid, &kvm->arch.mmu); > + return 0; > } > > static bool kvm_is_device_pfn(unsigned long pfn) > diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig > index b74916de5183..484d0873061c 100644 > --- a/virt/kvm/Kconfig > +++ b/virt/kvm/Kconfig > @@ -62,9 +62,6 @@ config HAVE_KVM_CPU_RELAX_INTERCEPT > config KVM_VFIO > bool > > -config HAVE_KVM_ARCH_TLB_FLUSH_ALL > - bool > - > config HAVE_KVM_INVALID_WAKEUPS > bool > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 277507463678..fefd3e3c8fe1 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -347,7 +347,6 @@ bool kvm_make_all_cpus_request(struct kvm *kvm, unsigned int req) > } > EXPORT_SYMBOL_GPL(kvm_make_all_cpus_request); > > -#ifndef CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL > void kvm_flush_remote_tlbs(struct kvm *kvm) > { > ++kvm->stat.generic.remote_tlb_flush_requests; > @@ -368,7 +367,6 @@ void kvm_flush_remote_tlbs(struct kvm *kvm) > ++kvm->stat.generic.remote_tlb_flush; > } For context, we currently have this: if (!kvm_arch_flush_remote_tlb(kvm) || kvm_make_all_cpus_request(kvm, KVM_REQ_TLB_FLUSH)) ++kvm->stat.generic.remote_tlb_flush; Is there any reason why we shouldn't move the KVM_REQ_TLB_FLUSH call into the arch-specific helpers? This is architecture specific, even if the majority of the supported architecture cannot do broadcast invalidation like arm64 does. Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel